The present invention relates to pulsed wave (PW) spectral Doppler ultrasound. Spectral Doppler ultrasound imaging provides an image of velocities (vertical axis) values modulated by energy as a function of time (horizontal axis). This spectrum may be used for studying fluid flow or tissue motion within a patient. By transmitting a plurality of pulses at a single gate location, a spectral Doppler response is generated in response to received echo signals. The frequency spectrum of the object's motion or flow for a single spatial region is estimated and displayed as a function of time.
Sonographers manually adjust the gate location, gate size, transmit frequency and other spectral Doppler imaging control parameters in order to acquire a desirable image. The gate placement is assisted by display of a 2D B-mode image of the anatomy of interest. Some processes have been proposed for automatic placement of the spectral Doppler gate using B-mode or color Doppler (F-mode) information. However, obtaining the B-mode or F-mode information interrupts the acquisition of the relatively high pulse repetition frequency PW Doppler. A brief interruption (e.g., 10-20 ms) allows at least a portion of the two or three-dimensional B-mode or F-mode data to be acquired. This produces gaps in the PW Doppler measurement. Depending on the temporal characteristics of the PW Doppler waveform due to flow dynamics, vital information may be lost during this time interval.